5. Решите уравнения: A) 2x + (x + 3) = 9; б) 3(2x+5) -6 = 12

Решение:

1. \(2x + (x + 3) = 9\)
   \(2x + x + 3 = 9\)
   \(3x = 9 - 3\)
   \(3x = 6\)
   \(x = 6 : 3\)
   \(x = 2\)
2. \(3(2x+5) - 6 = 12\)
   \(3(2x+5) = 12 + 6\)
   \(3(2x+5) = 18\)
   \(2x+5 = 18 : 3\)
   \(2x+5 = 6\)
   \(2x = 6 - 5\)
   \(2x = 1\)
   \(x = 1 : 2\)
   \(x = 0,5\)

Ответ: а) x = 2; б) x = 0,5.